A takeoff of an aircraft from a runway may be rejected for a variety of reasons, such as engine failure, activation of a takeoff warning horn, direction from air traffic control, blown tires, system warnings, and the like. For takeoff, currently-known autobraking systems are placed in a rejected takeoff (“RTO”) mode. With a currently-known autobraking system in the RTO mode, a pilot typically can initiate a rejected takeoff maneuver by returning throttles to the “idle” position or by engaging reverse thrust.
Currently-known autobraking systems for large aircraft provide maximum braking pressure when a rejected takeoff is initiated. Characteristic of all rejected takeoffs is the objective of stopping the airplane within the remaining runway. Maximum braking is applied, typically at speeds above 85 knots, independent of the amount of runway remaining or the amount of headwind or temperature. During maximum braking, aircraft brakes absorb the braking energy and can become very hot. Absorption of the braking energy can cause brake over-temperature, brake fires, fuse plug melting, tire destruction, and subsequent runway closures. These results of brake energy absorption can lead to increased costs, decreased safety, and other issues for airlines and controlling agencies.
The rejected takeoff function of currently-known autobraking systems applies maximum braking without controlling deceleration and without consideration to application of less than maximum braking pressure. Thus, some of the consequences of absorption of brake energy can be incurred unnecessarily in instances when a rejected takeoff is initiated but the aircraft can be stopped on the remaining runway with application of less than maximum brake pressure.
The foregoing examples of related art and limitations associated therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.